1. Field of the Invention
This invention relates in general to communication systems, and more particularly, to a method and system for managing information communicated over a Simple Integrated Media Access (SIMA) network with a Nominal Bit Rate (NBR) pool.
2. Description of Related Art
Simple Integrated Media Access (SIMA) is a new way of introducing new properties for packet-based data networks, such as TCP/IP or ATM networks. The basic idea of SIMA relies on the use of eight packet-discarding priority levels, as described in details in the above-mentioned patent applications, entitled "NOMINAL BIT RATE NETWORK SERVICE", NC 7664, Ser. No. 08/821,273, filed Mar.20, 1997; U.S. patent application entitled "CELL SCHEDULING SYSTEM AND METHOD FOR NETWORK NODES", NC 7665, Ser. No. 08/822,266, filed Mar. 20, 1997; and U.S. patent application entitled "ACCOUNTING SYSTEM AND METHOD FOR A NOMINAL BIT RATE NETWORK SERVICE", NC 7701, Ser. No. 08/822,270, filed Mar. 20, 1997; the subject matter of which are hereby incorporated by reference. Every data packet is equipped with a priority level (PL) that can be an integer between 0 and 7. In the latest SIMA literature, the term "priority level" is often replaced by "drop preference" which has the same meaning as "priority level".
In a SIMA network, priority is used for selecting packets that are discarded during congestion of a network node. The priority is determined from the ratio of a momentary actual bit rate of the source (a customer) to the Nominal Bit Rate (NBR) assigned to the source (the customer). This determination is performed in a network access node that is the first network element to receive a packet from a customer equipment.
A conventional way of managing customer charging on Internet is based on flat- rate, that is, each customer pays a monthly fee and gets certain Internet service. Since the management of a more complicated charging scheme for every individual customer means excessive management and cost, the flat-rate charging scheme is currently a prevalent way.
SIMA network with this type of simple flat-rate charging scheme is presently available for the customer. The monthly fee, for example $X, is translated to a certain NBR. The available network capacity is then divided among competing connections proportional to the NBR of each connection or customer. With typical data applications and low bit rate real-time applications, this SIMA network system may work properly. However, if a SIMA customer has, for instance, a permanent or flat-rate NBR of 50 kbit/s, and he/she desires to send a video stream with a speed of 500 kbit/s (i.e. higher NBR), the outcome could be totally unsatisfactory in using the simple flat-rate charging scheme. The priority of the packets (or called frames or cells) of information will be so low that the packet loss ratio will be very high. Consequently, the video quality will be very low for any practical purpose. This problem can be solved by combining the flat rate scheme and a time-dependent charging scheme presented in the above-mentioned U.S. patent applications. Although this solution is technically quite simple, it requires many changes in customer's management and charging. For example, the customer has to keep track of what period of time that he/she has requested for what NBR, other than the permanent NBR, and how much it is for such NBR, etc.
Accordingly, there is a need in the communication industry for a network management architecture and method that can combine the simplicity of flat-rate charging and the flexibility of time-dependent scheme into a SIMA network system.